Automated equipment is typically employed in industry to process, print and sort sheet material for use in manufacture, fabrication and mailstream operations. One such device to which the present invention is directed is a mailpiece sorter which sorts mail into various bins or trays for delivery.
Mailpiece sorters are often employed by service providers, including delivery agents, e.g., the United States Postal Service USPS, entities which specialize in mailpiece fabrication, and/or companies providing sortation services in accordance with the Mailpiece Manifest System (MMS). Regarding the latter, most postal authorities offer large discounts to mailers willing to organize/group mail into batches or trays having a common destination. Typically, discounts are available for batches/trays containing a minimum of two hundred (200) or so mailpieces.
The sorting equipment organizes large quantities of mail destined for delivery to a multiplicity of destinations, e.g., countries, regions, states, towns and/or postal codes, into smaller, more manageable, trays or bins of mail for delivery to a common destination. For example, one sorting process may organize mail into bins corresponding to various regions of the U.S., e.g., northeast, southeast, mid-west, southwest and northwest regions, i.e., outbound mail. Subsequently, mail destined for each region may be sorted into bins corresponding to the various states of a particular region e.g., bins corresponding to New York, New Jersey, Pennsylvania, Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire and Maine, sometimes referred to as inbound mail. Yet another sort may organize the mail destined for a particular state into the various postal codes within the respective state, i.e., a sort to route or delivery sequence.
The efficacy and speed of a mailpiece sorter is generally a function of the number of sortation sequences or passes required to be performed. Further, the number of passes will generally depend upon the diversity/quantity of mail to be sorted and the number of sortation bins available. At one end of the spectrum, a mailpiece sorter having four thousand (4,000) sorting bins or trays can sort a batch of mail having four thousand possible destinations, e.g., postal codes, in a single pass. Of course, a mailpiece sorter of this size is purely theoretical, inasmuch as such a large number of sortation bins is not practical in view of the total space required to house such a sorter. At the other end of the spectrum, a mailpiece sorter having as few as eight (8) sortation bins (i.e., using a RADIX sorting algorithm), may require as many as five (5) passes though the sortation equipment to sort the same batch of mail i.e., mail to be delivered to four thousand (4,000) potential postal codes. The number of required passes through the sorter may be evaluated by solving for P in equation (1.0) below:P(# of Bins)=# of Destinations  (1.0)
In view of the foregoing, a service provider typically weighs the technical and business options in connection with the purchase and/or operation of the mailpiece sortation equipment. On one hand, a service provider may opt to employ a large mailpiece sorter, e.g., a sorter having one hundred (100) or more bins, to minimize the number of passes required by the sortation equipment. On the other hand, a service provider may opt to employ a substantially smaller mailpiece sorter e.g., a sorter having sixteen (16) or fewer bins, knowing that multiple passes and, consequently, additional time/labor will be required to sort the mail.
The principal technical/business issues include, inter alia: (i) the number/type of mailpieces to be sorted, (ii) the value of discounts potentially available through sortation, (iii) the return on investment associated with the various mailpiece sortation equipment available and (iv) the cost and availability of labor. FIG. 1 depicts a conventional linear mailpiece sorter 100 having a plurality of sortation bins or collection trays 110 disposed on each side of a linear sorting path SP. In operation, the mailpieces 114 are first stacked on-edge in a feeder module 116 and fed toward a singulation belt 120 by vertical separator plates 122. The plates 122 are driven along, and by means of, a feed belt 124 which urges the mailpieces 114 against the singulation belt 120. As a mailpiece 114 engages the singulation belt 120, the mailpiece 114 is separated from the stack and conveyed along the sorting path SP. Inasmuch as the singulation belt 120 and sorting path SP are disposed orthogonally of the feed path FP, each mailpiece 114 may be conveyed directly along the sorting path SP without any further requirements to manipulate the direction and/or orientation of the mailpiece 114, e.g., a right-angle turn.
As each mailpiece 114 is conveyed along the sorting path SP, a mailpiece scanner 126 typically reads certain information i.e., identification, destination, postal code information, etc., contained on the face of the mailpiece 114 for input to a processor 130. Inasmuch as each of the sortation bins or trays 110 correspond to a pre-assigned location in the RADIX sortation algorithm, the processor 130 controls a plurality of diverter mechanisms 134 (i.e., one per bin/tray 110) to move into the sorting path SP at the appropriate moment time to collect mailpieces 114 into the trays 110. That is, since the mailpiece sorter 110 knows the identity and location of each mailpiece 114 along the sorting path SP, the processor 130 issues signals to rapidly activate the diverter mechanisms 134 so as to re-direct a particular mailpiece 114 into its pre-assigned collection tray 110. A linear mailpiece sorter of the type described above is manufactured and distributed by Pitney Bowes Inc. located in Stamford, State of Connecticut, USA, under the tradename “Olympus II”.
As mentioned in a preceding paragraph, the total space available to a service provider/operator may prohibit/preclude the use of a large linear mailpiece sorter such as the type described above. That is, since each collection tray 110 must accommodate a conventional type-ten (No. 10) mailpiece envelope, each tray 110 spans a distance slightly larger than one foot (1′) or about fourteen inches (14″), corresponding to the long edge of the rectangular mailpiece 114. As a result, a linear mailpiece sorter can occupy a large area or “footprint”, i.e., requiring hundreds of lineal feet and/or a facility competing with the size of a conventional aircraft hanger.
In an effort to accommodate service providers with less available space/real estate, other mailpiece sortation devices are available which employ a multi-tiered bank of collection trays (i.e., arranged vertically). These sortation devices (not shown) include an intermediate elevation module disposed between the feeder and bank of collection trays. More specifically, the elevation module includes a highly inclined table or deck for supporting a labyrinth of twisted conveyor belt pairs. The belt pairs capture mailpieces therebetween and convey mailpieces along various feed paths which are formed by a series of “Y”-shaped branches. Each Y-shaped branch/intersection bifurcates or diverts mailpieces to one of two downstream paths, and additional branches downstream of each new path increase the number of paths by a factor of two. Further, each branch functions to change the elevation of a mailpiece to feed the multi-tiered arrangement of collection trays. A multi-tiered mailpiece sorter of the type described above is manufactured and distributed by Pitney Bowes Inc. located in Stamford, State of Connecticut, USA, under the tradename “Olympus II”.
Multi-tiered mailpiece sorters can significantly reduce the space/footprint required by linear mailpiece sorters, though such multi-tiered sorters are costly to fabricate, operate and maintain. Typically, these multi-tiered mailpiece sorters are nearly twice as costly to fabricate and maintain as compared to linear mailpiece sorters having the same or greater sorting capacity.
In addition to the difficulties associated with space and expense, the mailpiece sorters described above are highly complex, require highly-skilled technicians to perform maintenance and, if not maintained properly, can result in damage to sorted mailpieces. For example, if particulate matter (e.g., paper dust) from envelopes is allowed to accumulate along the sorting path and/or in the actuation mechanisms of a diverter, the mailpiece sorter can become prone to paper jams. Further, inasmuch as the mailpieces travel at a high rate of speed along the sorting path SP, the mailpieces can be damaged or jammed when re-directed by the by the diverter mechanism. Moreover, in addition to damage caused by jamming, the sortation order of the mailpieces, which is critical to perform a RADIX sort, can inadvertently be altered.
A need, therefore, exists for a sheet material sorter and sortation bin module therefor which reduces the sorter footprint for space efficiency and provides a smooth conveyance/diversion path for preventing damage and paper jams along the feed path.